Method of accelerating the vulcanization of rubber and product thereof



memes Jul 12, 1927. y

unirsu sra'lss PATENT OFFICE.

LORIN B. SEBR ELL, 'OF AKRON, OHIO, ASSIGNOR TO THE GOODYEAR TIRE &RUBBER COMPANY, OF AKRON; OHIO, A CORPORATION OF OHIO.

METHOD OF ACCELEEATING THE VULCANIZATION' OF RUBBEER AND PRODUCTTHEREOF.

No Drawing. Original application-filed April 4, 1924, Serial No.704,159. Divided. and this application I flled september 1c, 1926.Serial No. 135,992.

My invention relates to a method of vuloanizing rubber and rubber-likecompositions, and it is particularly directed to a novel method ofaccelerating the vulcanizing process.

It has heretofore been suggested that certain thiazole compoundscelerators for the vulcanization of rubber. These accelerators areespecially desirable because of their power, since they possess anability to promote the vulcanization of rubber much more rapidly thanmany accelerators now known. By reason of this ability, it is possible,if desired, to reduce the temperature of vulcanization, which has beenfound to improve the physical characteristics of the vulcanized rubber.Moreover,

certain of the thiazoles also appear to improve the agingcharacteristics of rubber or rubber compounds, which, of course, is aparticularly desirable feature.

In Patent No. 1,544,687, certain aryl thiazole compositions areenumerated which are particularly adapted for use in the acceleratingprocess. It is the object of this invention to set forth a specificclass of compositions falling within the broad class therein disclosedwhich is remarkably well adapted to be utilized as an accelerator ofvulcanization.

The materials made the subject of the present invention are the mercaptodimethyl benzothiazoles and their derivatives, a specific embodiment ofwhich is l-mercapto it-ii-dimethyl benzothiazole and may be representedstructurally as follows:

oagLV l s provide efficient acforms in needle-shaped crystals having amelting point of 193 C. These materials, as well as the metallicderivatives, such as the zinc and lead salts, are valuable acceleratorsof vulcanization.

When, for example, a rubber composition having the following ratio ofingredients 100 parts-rubber, 5 parts zinc oxide, 3 parts sulphur, 1part accelerator is Vulcan ized with steam maintained at 40 poundspressure, a satisfactory cured product whose breaking load is 182kilograms per square centimeter is obtained in 10 minutes. When the samecomposition is subjected to steam at 20 pounds pressure for thirtyminutes, a well cured product is obtained whose tensional strength atbreaking load is 211 kilograms per square centimeter.

From the foregoing description, it will be apparent that the dimethylbenzothiazole derivatives are possessed ofdesirable acceleratingproperties. Moreover, it will likewise be apparent that although I haveenumerated but a few derivatives of the dimethyl mercapto benzothiazole,the invention is not so limited, but is susceptible to numerousmodifications without departing from its scope, and I desire that it belimited only to accord with the prior art andthe appended claims.

The .present application is a division of a prior application No.704,159 filed Apr. 4, 1924, now patented as Serial No. 1,604,199.

What I claim is:

1. A method of accelerating the vulcanization of rubber that comprisesvulcanizing the same in the presence of a l-mercapto dimethylbenzothiazole, or a derivative thereof.

- 2. A method of accelerating the vulcanization of rubber that comprisesvulcanizing the same in the presence of l-mercapto- Pip-dimethylbenzothiazole, or a derivative thereof.

3. A method of accelerating the vulcanization of rubber that comprisesvulcanizing the same in the presence of. a metallic salt of1-mercapto-3-5-dimcthyl bcnzothiazole.

4-. A method of accelerating the vulcanization of rubber that comprisesvulcanizing the same in the presence of a bivalent metallic salt ofl-mercapto-3-5-dimethyl benzothiazole.

5. A method of accelerating the vulcaniza-.

' dimethyl benzothiazole polysulphide.

8. A rubber product which has been vulcanized in the presence of al-mercapto dimethyl benzothiazole or a derivative thereof.

9. A rubber product'which has been vulcanized in the presence of al-mercapto-3-5- dimethyl benzothiazole or a derivative thereof.

10. A rubber product which has been vul canized in the presence of ametallic salt of 1-mercapto-3-5-di1nethy1 benzothiazole.

In witness whereof I have hereunto signed my name.

LORIN B. SEBRELL.

